1. Field of the Invention
The present invention relates to a marine propulsion system and a marine vessel having the same.
2. Description of the Related Art
General marine propulsion systems obtain thrust by mechanically driving a screw etc. For example, they obtain thrust by transmitting power generated by a prime mover to a screw by a shaft system so as to turn it in the air or water.
Contrarily, the marine propulsion system disclosed in Japanese Patent No. 3366663 obtains thrust by supplying high pressure gas from the bottom of the hull into the water at the rear.
A marine propulsion system obtaining thrust by mechanically driving a screw etc. has the disadvantage that the structure is complex and the system is apt to become large in size. Further, mechanical loss occurs, so there is the disadvantage that the energy efficiency is low. Further, when the relative speed of the blades of the screw and the flowing water becomes large, the water becomes aerated, that is, the phenomenon referred to as “cavitation” occurs, so there is a limit to the increase of the propulsion speed. In addition, when using as the prime mover a diesel engine or other internal combustion engine, a gas such as carbon dioxide is discharged into the air, so there is also the disadvantage that the exhaust becomes a cause of air pollution.
On the other hand, the marine propulsion system disclosed in Japanese Patent No. 3366663 burns air raised in pressure using for example a compressor together with the fuel in a combuster to obtain a high temperature and high pressure gas. For this reason, a prime mover for driving the compressor becomes necessary, so there is the disadvantage that the device is apt to become large in size. Further, loss occurs along with the drive operation of the compressor, so there also exists the disadvantage that the energy efficiency is low.